Armored trains - a symbol of military might of the turn of the 20th century
- are impractical, easily sabotaged, and expensive to operate. But they
sure look menacingly cool! Take, for example, this humongous railway gun
TM-3-12 which used a gun from a battleship mounted on a train chassis.

Dark Roasted Blend has a nifty gallery of this and many other examples
of armored train: Link
- Thanks Avi!